Related lists

Description

FischerTechnik is a construction toy from Germany that's similar to Lego Technic. Actually it's the other way around: FischerTechnik existed long before Lego started to make Technic boxes in the 1980s. I made a FischerTechnik clock a while ago and decided to put the construction pictures online here.

Details

The build instructions show you how to build the mechanism, without any hardware or software to keep track of time. The project logs describe how you could make this clock (or a similar one) work with a mains-based pulse generator, or (like I did) with an Arduino and a GPS module.

There is one mechanical feature that's "unique" about this clock (though I'm sure I'm not the first to think of this): unlike other mechanical clocks that usually use some sort of friction coupling to adjust the time, this clock uses a differential and a second motor. While
the clock is operating normally, the differential is held stationary,
so the rotation on one axle is propagated to the other axle (in opposite direction but that doesn't matter). But while
adjusting the time, the time adjustment motor rotates the differential while the time keeping motor stays still.

Components

Project Logs

As I mentioned in my last log, the FischerTechnik clock presented in this project can't run without some electronics. I already explained that the clock can run with just a pulse generator that advances the hands by a minute, once a minute. But I wanted to go a little further. I wanted the clock to set itself to the correct time, and stay accurate as long as it was running.

Keeping accurate time on an electro-mechanical clock can be a challenge. There are 86400 seconds in a day, so even if the clock would run fast or slow by only 0.1%, it would still be off by almost a minute and a half per day.

Build Instructions

These are the FischerTechnik parts you need to build the clock, except for the switches that are used to detect that he hands are in the 12 o'clock position. I used my Hobby1, Hobby2 and Computing (1987) boxes. You don't need the (black) base plate shown in the background, that's just a box I used for better contrast in the pictures. The electronics to turn motors on and off and keep track of time aren't part of the build instructions, they are covered by the Project Logs.

2

Step 2

The first part of the main frame.

3

Step 3

More main frame, and the 10-tooth gear that drives 10:40 reduction for the hour hand.